This project proposes to study the effects of interstitial lung disease on ventilation-to-perfusion distribution. The project is defined in 3 specific aims and phases: 1. An accurate, efficient method of quantitating VA:Q distribution in vivo will be developed by combining a current method which uses multiple inert gases (Wagner method), together with a specially developed mass spectrometer for continuous in vivo analysis; 2. Normal standards for VA:Qc distribution - across various age groups and at rest and exercise - will be established; 3. VA:Qc distribution in interstitial lung disease will be described in patients with Farmer's Lung Disease (acute through chronic stages); and, in an animal model, the time-course of functional to morphologic changes will be correlated. BIBLIOGRAPHIC REFERENCES: Gledhill, N., Fraese, A., Harwood, H., Dempsey, J. A. Distribution of Ventilation: Perfusion Ratios in Man During Hypoxia and Exercise. Fed. Proc., 35;1501, 1976 (abstract). Mastenbrook, S. M., Stewart, W. E., and Dempsey, J. A. Ventilation-perfusion Ratio Distributions: Graphical Assessment From Inert Gas Elimination Data. (Abstract accepted for presentation at 29th ACEMB National Meeting, Boston, Mass., Nov. 1976).